whole, desirable, it must be .admitted that frequent changes, implying generally 

 the introduction of inexperienced persons, cannot fail to ho detrimental to the 

 accuracy and value of the work and it is lioped they may be rare in the future. 



The hours of observation for the j'car 18S0 were the same as during tiie 

 year 1879. With the beginning of the year 1881, liowcver, the hours were 

 changed and the number of daily observations increased to si.\. 'J'hcy are at present 

 as follows; G a. m. 10 a. m. 2 p. m. 6 p. m. 9-27 p. m. and H p. in. The change 

 from 10 p. m. to 9-27 p. m. was rendered necessary in order to make that obser- 

 vation agree with the "international hour" which has been changed in accordance 

 with the desire of the chief of the U. S. Signal Service. 



In the prejiaration of the report for this year tlie aim has been to arrange 

 it that comparison between it and that for the previous year would be easy. 

 The tables are, therefore, in general, arranged in the same manner and corres- 

 ponding tables are indicated b}' the same letter of the ali)habet. The charts are 

 also given numbers corresponding to those of last year and comparison of these 

 graphical representations of the meteoi'ological phenomena for the two years 

 will be easily made. Finally a sgries of charts is given, showing the means of a 

 portion of the observations for the two j'cars and a comparison of these with 

 tliose for the present year is interesting as indicating a considerable degree of 

 constancy on the part of several of the meteorological elements, that is, so far 

 as can be established from the results of two years' observations. Hourly obser- 

 vations were maintained during the months of March, June, September an<l 

 December. These four months, it is believed, afford a good representation of 

 the varying meteorological conditions of the year, but it is intended to continue 

 the hourly observations during several months of the year 1881. 



During the first week in August-an expedition to the summit of Fujinoyama 

 was made by the special students in the Department of Physics, accompanied 

 by Professor W. S. Chajilin of the Department of Civil Engineering, and the 

 writer. The special object of the expedition was the determination of the force 

 of gravity on the summit of the mountain. At the same time a series of mete- 

 orological observations was made during the stay of the party upon the mountain. 

 The value of these has been greatly enhanced by the addition of a series of 

 barometrical observations made at the same time by Jlessrs Nakamr.ra and 

 Wada of the Surveying Department who carried out a series of simidtaneous 

 observations on the summit of the mountain and at the sea level near the base. 

 I am greatly indebted to Messrs Nakamura and Wada for their kindness in fur- 

 nishing these observations to be made use of in this report in any desirable 

 manner. Taken all together, these meteorological observations are, of course, 

 of considerable value as affording a means of computing the height of the moun- 

 tain. To that end Prof Chaplin has kindly consented to discass them in con- 

 nection with others, bearing upon the same point, which lie has been able to 

 secure and the paper in which lie has contributed the result of this discussion 

 will be found to be one of the most interesting and valuable portions of this report. 



